1. Field of the Invention
The present invention generally refers to the provision of broadband telecommunication services. In particular, the present invention refers to a method for designing a broadband telecommunication service based on a technology of the xDSL (“generic Digital Subscriber Line”) type for a subscriber loop on which nowadays only traditional POTS or ISDN (“Plain Old Telephone Service” or “Integrated Services Digital Network”) telephone systems are provided.
2. Description of the Related Art
The exponential increase in the popularity of the Internet and of related data services has prompted service providers in the Public Switched Telephone Network (PSTN), to seek new technologies to deliver high speed data services to their customers. One solution is provided by DSL (Digital Subscriber Line) technologies. Several DSL technologies offer high speed services over existing copper facilities commonly referred to “subscriber loops”. Such technologies include ADSL (“Asymmetrical Digital Subscriber Line”); HDSL (“High-bit-rate Digital Subscriber Line”); RDSL (“Rate Adaptive Digital Subscriber Line”); SDSL (“Symmetric Digital Subscriber Line”); and VDSL (very High-speed Digital Subscriber Line”). These DSL or similar technologies are collectively known as “xDSL” services.
A problem encountered in the provision of xDSL services is that subscriber loops have largely been neglected from a technology upgrade perspective. Existing subscriber loops and the structure of the copper distribution network were originally designed for narrow band voice telephony and not to support high speed data services. Consequently, the electrical characteristics of the cables and subscriber loops set limits to the provision of broadband services: for example, many subscriber loops include wire gauge changes and bridged taps (unused extension lines) which limit the available bandwidth, limiting the performance of the loops with respect to the delivery of an xDSL service.
U.S. Pat. No. 6,266,395 discloses a method and an apparatus for single-ended qualification of subscriber loops for xDSL services. The method involves first screening a subscriber loop database for disqualifying devices or services, associated with that loop, which are incompatible with xDSL services. If none are found, a set of predetermined electrical characteristics of the subscriber loop are derived from information in the database, or directly measured using test equipment at a central office end of the subscriber loop. The electrical characteristics are used to calculate an available bandwidth for xDSL services on the subscriber loop.
In W0 02/21742 a system is disclosed that is able to predict the performance of a DSL line on an already installed telephone loop. The system obtains a topologic description of the already installed telephone loop and through it, it identifies an equivalent loop. Afterwards, the system determines DSL performance for the equivalent loop. From DSL performance of the equivalent loop, the system predicts DSL performance for the already installed telephone loop.